Sonoran Desert

It’s the end of the third of four weeks of my Photography 101 class and today’s topic is landscape. I didn’t have a chance to get out and take a new landscape photo today, at least not the sweepingly magestic sort of image I think of when I think of landscape photography, so I’m posting one of my favorites from Arizona a few weeks ago:

Ah, southern Arizona. What an amazing place! The insects there are fabulous and I miss the joy I got from spotting my first palo verde beetle of the year (and bringing it in the house to terrorize my husband), hearing dozens of June bugs buzzing around the trees, and the desert cicadas that make an enormous racket in the hottest part of the middle of the day. I loved the aquatic insects and the dragonflies, all the strange desert insects I could only find there. Not that I don’t love North Carolina – I really do – but I lived in Arizona for 20 years altogether and some of my best memories are from that crazy, wild, spiky place. It’s hard not to miss it, at least now and again.

Have a great weekend, everyone! Me, I’ll be at work the next few days. But, if you have to work through the weekend, it’s nice to work at a natural history museum field station with a wealth of interesting biological phenomena to observe. I still feel lucky, everyday.

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When I’ve done my summer field work, it typically involves getting up early in the morning and driving out to a pond in the desert to collect giant water bug eggs. It’s the monsoon season, so the weather is wildly unpredictable, but it does make for some very gorgeous views:

Sun coming up on saguaros with monsoon clouds in the background

I’ve lived in Arizona the majority of my life, but I never get tired of looking at saguaros. They’re just so darned stately! Really going to miss them when I move on.

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It’s that time of year again! Time for the palo verde beetles to descend on Tucson and fill the night sky with giant beetles flying around drunkenly looking for mates. I already wrote a post about how much I love these beetles and promised to write more about their biology. Today I am making good on that promise!

I think these beetles are one of the best parts of living in the Sonoran Desert. Each summer when the monsoons begin, these beetles start to appear. They’re large, dark brown nocturnal beetles, 3 – 3.5 inches long. Check out the long, luxurious antennae:

Palo verde beetle antenna

Palo verde beetles belong to the beetle family Cerambycidae, the longhorn beetles. You can see how the family got its common name! Nearly all members of the group have these long antennae, including several important wood pest species (such as the Asian longhorn beetles). The palo verde beetle is no exception.

I think the palo verde beetles look rather fierce. Check out the spikes on the thorax:

Palo verde beetle thorax

And the big pinching mouthparts (called mandibles):

Palo verde beetle jaws

In spite of their size, their armor, and the powerful jaws, these beetles are largely harmless. That’s not to say that they won’t flail about wildly and try to bite you if you pick them up, and they can deliver a strong, painful pinch if you’re not careful. (That’s never stopped me from picking them up!) Mostly though, the beetles use those impressive mandibles for fighting and/or mating. I posted a photo of a male and a female palo verde beetle struggling with each other before they mated a while back and jaws were used extensively as the male subdued the female. In fact, she lost a leg and both antennae in the struggle. Those strong jaws are also used by males in battles with one another to win females. The better fighter a male is, the more females he has a chance to mate with.

There’s one thing the jaws aren’t used for though: feeding. Adult palo verde beetles don’t feed at all and rely on nutrient reserves they ingested as larvae to fuel their adult activities. As result, their adult lifespans are pretty short, less than a month. During that month, they fly around (not very well and in the dark – there’s nothing quite like seeing one of these flying toward your head at night!), fight, mate, and lay eggs. That’s a lot to do for a large flying animal that doesn’t eat!

Once a male finds and mates with a female, the female will burrow into the soil at the base of trees and lay her eggs about a foot down. When the eggs hatch, the larvae feed on the roots of the trees, focusing on the starches within the roots. After 2-3 years of feeding and growing, the larvae are enormous and look like this:

Palo verde beetle larva! This one was over 3 inches long.

The larvae have strong and powerful mouthparts too, essential for cutting trees roots open so they can eat. When they’ve grown large enough, they pupate underground. The adult emerges when the monsoons arrive and dig their way up to the surface, leaving large round holes around the base of the tree where they grew up. Then they go about the serious business of flying around in the dark (scaring a lot of people in the process), looking for mates, and starting the whole process all over again.

Palo verde beetles get their name from the palo verde tree, a gorgeous desert tree with green bark native to the Sonoran Desert. If you dig up palo verde trees, you will supposedly nearly always find several palo verde beetle larvae happily munching away on the roots. Because they are root borers and root borers are commonly associated with dead, dying, or unhealthy trees, palo verde beetles are often considered pests. If you search the internet, you’ll find all sorts of crazy ideas for how to rid your yard of these “dangerous” beetles so that they don’t kill your trees. It all a bit sensationalistic though! Palo verde beetles DO eat roots of trees, but consider this: there are millions of palo verde trees in the Sonoran Desert and nearly all of them have several palo verde beetle larvae gnawing on their roots. If the beetles are really destroying tress, wouldn’t there be fewer palo verde trees around? Palo verde beetles can cause some damage to trees, especially non-native ornamentals, but usually only in trees that are already having problems. The best defense against palo verde beetle damage is taking care of your trees! If you keep young trees healthy by watering them regularly and fertilizing, they will usually be able to withstand palo verde beetle larvae eating their roots quite well.

While I completely understand why people might be scared of these lumbering, giant beetles – they are VERY large after all – I can’t help but love them! I associate them with lazy, hot summers and the arrival of the much-needed rains. They’re hilarious to watch flying around. And they’re stunning! As proof, I leave you with this last image:

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Warning: The creepy factor of today’s post is going to be quite high. Just want to give you a head’s up before you dive in.

The Sonoran Desert is an amazing place! It’s greener than people expect, we’ve got awesome giant cacti like the saguaro, and the diversity of life is astounding. Many entomologists think southern Arizona and northern Mexico are among the best places to study and/or collect insects in the world, and people come from all over specifically to check out our insects. (People also come from all over to stay warm during the winter, but that’s a story for another time!) Of course, Arizona is also known for several other animals, some of which can actually be dangerous if you’re not careful, like the rattlesnake in the photo, or just plain scary for a lot of people.

I freely admit that these things scare the daylights out of me. They’re fast, they’re enormous (up to 8 inches long!), and there’s something about those legs that I find incredibly disturbing. (It’s not the number – millipedes don’t bother me at all – but the way they move…) Still, you have to admire this animal. They have stunning coloration that even I can appreciate. They’re fierce predators, using their modified forelegs (called forcipules) to inject venom into their prey and paralyze them before they chew them up. Watching one of these things eat is both horrifying and awe-inspiring! Plus, you have to respect any arthropod that gets this big. I’m always amazed when I see them running around the desert at night – and very, very thankful that my tent has a good zipper on it!

Desert Blond Tarantula, Aphonopelma chalcodes

Aphonopelma chalcodes

I find that people who are scared of spiders are often able to appreciate tarantulas. It probably helps that they move slowly and are generally harmless to people, plus they look fuzzy enough to be stuffed animals. I think tarantulas are great! Desert blond tarantulas tend to stay near their underground burrows to hunt, though males can venture further when searching for females, especially after monsoon storms. I think the coolest thing about these spiders is how they defend themselves from predators. When disturbed, they will brush their hind legs over the top of their abdomens, which releases a cloud of hairs. These hairs have hooked barbs on them, which means they embed themselves into the eyes, mouths, and noses of things that think a tarantula might make a tasty treat. The embedded hairs are known to be terribly irritating. Although I have not experienced this defense first hand, I have a feeling it’s rather like getting the tiny spines from prickly pears stuck in your fingers, i.e. really, really annoying!

Sun Spider or Solifugid, Eremobates sp.

Slightly blurry photo of an Eremobates solifugid

Solifugids are rather creepy looking arachnids, but you just have to love them! Also known as sun spiders or camel spiders, solifugids can get quite large in certain parts of the world. In the Sonoran Desert, they can approach 2 inches in length, but I rarely see any that big. Solifugids are predators and they can chase down their prey with those long, fast legs. The blurry photo is the result of this solifugid stalking a cricket and refusing to sit still! That pointy black bit up at the front is the business end of the solifugid, powerful mouthparts they use to rip apart their prey before they liquefy their food and eat the resulting soupy mess. These animals are often erroneously said to be dangerous to humans, but they really can’t do much to you except bite. Honestly though, who’s going to pick up an animal that looks like this and give it a chance to bite them? I love to watch them, but I leave these guys alone.

Vinegaroon, Mastigoproctus giganteus

Mastigoproctus giganteus

Vinegaroons, also known as whip scorpions, are gnarly looking beasts, but their scary looks belie their laid back demeanor! They’re not venomous, they generally don’t bite people, and they can become quite docile. Even I’m willing to handle these, and I’m a total wimp when it comes to picking up arachnids! Vinegaroons are fascinating animals. Those big, thick projections off the front end are mouthparts called pedipalps, powerful pincers used to capture prey (arthropods and some small vertebrates). Notice that the vinegaroon in the photo is standing on only 6 legs instead of 8. That’s because the front legs have been modified into sensory structures similar to insect antennae! The tail in the back allows the vinegaroon to protect itself from predators, though it isn’t a stinger. Instead, vinegaroons have glands near the end of the abdomen that store a mixture of acids, including acetic acid (the acid that gives vinegar its distinctive smell and taste – hence vinegaroon!). When disturbed, the vinegaroon points its tail at the predator and ejects some acid from the glands. The acid travels up the tail and sprays the predator in the face. As you might imagine, getting a face full of acid spray will slow most animals down, giving the vinegaroon time to run away. Now tell me that’s not the coolest thing you’ve ever heard!

Arizona Stripetail Scorpion, Vaejovis spinigerus

Vaejovis spinigerus

Although many (maybe most) Arizonans are scared of all of the animals included in this post whether they’re harmful or not, I think the scorpion is probably the most feared of them all. We’ve got three common species of scorpions where I live, and all of them have painful stings. The bark scorpion can actually be life threatening under the right conditions, so it’s good to give these animals a lot of respect. Still, what a magnificent animal! Just looking at a scorpion should help you appreciate how very long these beasts have roamed the earth. There’s something incredibly primitive about them, yet look at the scorpion in the photo. Isn’t it stunning? With the morning light shining through its tail it’s almost pretty! My students found this little one half-frozen under a rock on a very cold morning after a frigid night of camping. We were enthralled by it and I’m glad I captured it in a photo so I will always remember how glorious this one was.

Even though I am scared to death of the centipedes and you really do have to look out for the scorpions to avoid getting stung, I love living in a place that has so many interesting animals! The fact that I’ve seen all of these live in the desert on several occasions makes me really happy and I think it’s a real treat to come across a vinegaroon or a solifugid while collecting insects or simply enjoying being outside. Isn’t nature spectacular?!